The influence of fibromyalgia on achieving remission in patients with long-standing rheumatoid arthritis.

To investigate the influence of fibromyalgia (FM) on achieving remission defined on the basis of the Simplified Disease Activity Index (SDAI) remission criteria in patients with long-standing rheumatoid arthritis (RA). This observational longitudinal cohort consisted of long-standing RA patients being treated with conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) or biological DMARDs (bDMARDs). After 6 months of follow-up, the patients fulfilling or not fulfilling the remission criteria were identified and compared with each other in terms of the presence of FM, neuropathic pain, and other comorbidities. At the end of the 6-month observation period, 24 of the 117 patients (20.4%) met the SDAI remission criteria. Logistic regression analysis showed that the modified Rheumatic Disease Comorbidity Index (mRDCI) (p = 0.0001), the FM presence (p = 0.0001), and the 36-item short-form health survey Mental Component Summary (SF-36 MCS) Score (p = 0.0088) were the strongest predictors of not being in SDAI remission. None of the patients with concomitant FM (17.1%) achieved SDAI remission. In comparison with the non-FM patients, the patients with RA and FM patients had worse scores on the SF-36 MCS (p = 0.011), on the sleep Visual Analogue Scale (VAS) (p = 0.018), on the self-counts of tender joints (p = 0.039), and on the PainDetect Questionnaire (PDQ) (p = 0.001). To avoid over treatment, an assessment of FM should be considered in RA patients who do not fulfil the remission criteria.